A light emitting assembly generally has a large planar substrate or plate with a plurality of light emitting sources which are mounted on the plate and which generate heat when emitting light. It is often desirable to remove generated heat so as to lower the temperature of the light emitting sources and the plate for reasons such as maintaining the light emitting sources within their optimal thermal operating conditions.
FIG. 1 illustrates such a type of conventional light emitting assembly having a vertical plate 100 with a plurality of light emitting sources 101 thereon. Heat generated by the light emitting sources 101 is dissipated by air flowing from the bottom of plate 100 through the middle and towards the top of the plate as indicated by arrow 103. As the air flows upwards, it is gradually heated by the light emitting sources 101 and/or the plate 100 such that the air has a higher temperature when it reaches the top of the plate 100 than at the bottom. This will adversely affect the efficiency of heat dissipation at the top, and may not be desirable in many circumstances.
Furthermore, due to the relatively ineffective heat dissipation at the top of the plate, the top may have a higher temperature than the bottom. For certain types of light emitting sources, for example, light emitting diodes, a higher temperature may result in a lower light emission. As such, the light emitting assembly 100 may have uneven light emission distribution along its height, which is often not desirable.
Heat sinks or heat pipes are generally used in conventional light emitting assemblies for enhancement of heat dissipation. However, such an extra mechanism may make the light emitting assembly unnecessarily bulky and heavy and may increase the production costs.
It is an object of the present invention to provide a light emitting assembly, which overcomes at least some of the deficiencies exhibited by those of the prior art.